A patient-centered 'test-drive' strategy for ankle-foot orthosis prescription: Protocol for a randomized participant-blinded trial.

BACKGROUND: Ankle-foot orthoses (AFOs) are commonly used to overcome mobility limitations related to lower limb musculoskeletal injury. Despite a multitude of AFOs to choose from, there is scant evidence to guide AFO prescription and limited opportunities for AFO users to provide experiential input during the process. To address these limitations in the current prescription process, this study evaluates a novel, user-centered and personalized 'test-drive' strategy using a robotic exoskeleton ('AFO emulator') to emulate commercial AFO mechanical properties (i.e., stiffness). The study will determine if brief, in-lab trials (with emulated or actual AFOs) can predict longer term preference, satisfaction, and mobility outcomes after community trials (with the actual AFOs). Secondarily, it will compare the in-lab experience of walking between actual vs. emulated AFOs. METHODS AND ANALYSIS: In this participant-blinded, randomized crossover study we will recruit up to fifty-eight individuals with lower limb musculoskeletal injuries who currently use an AFO. Participants will walk on a treadmill with three actual AFOs and corresponding emulated AFOs for the "in-lab" assessments. For the community trial assessment, participants will wear each of the actual AFOs for a two-week period during activities of daily living. Performance-based and user-reported measures of preference and mobility will be compared between short- and long-term trials (i.e., in-lab vs. two-week community trials), and between in-lab trials (emulated vs. actual AFOs). TRIAL REGISTRATION: The study was prospectively registered at www.clininicaltrials.gov (Clinical Trials Study ID: NCT06113159). Date: November 1st 2023. https://classic.clinicaltrials.gov/ct2/show/NCT06113159.

Transfemoral limb loss modestly increases the metabolic cost of optimal control simulations of walking.

Background: In transtibial limb loss, computer simulations suggest that the maintenance of muscle strength between pre- and post-limb loss can maintain the pre-limb loss metabolic cost. These results are consistent with comparable costs found experimentally in select cases of high functioning military service members with transtibial limb loss. It is unlikely that similar results would be found with transfemoral limb loss, although the theoretical limits are not known. Here we performed optimal control simulations of walking with and without an above-knee prosthesis to determine if transfemoral limb loss per se increases the metabolic cost of walking. Methods: OpenSim Moco was used to generate optimal control simulations of walking in 15 virtual "subjects" that minimized the weighted sum of (i) deviations from average able-bodied gait mechanics and (ii) the gross metabolic cost of walking, pre-limb loss in models with two intact biological limbs, and post-limb loss with one of the limbs replaced by a prosthetic knee and foot. No other changes were made to the model. Metabolic cost was compared between pre- and post-limb loss simulations in paired t-tests. Results: Metabolic cost post-limb loss increased by 0.7-9.3% (p < 0.01) depending on whether cost was scaled by total body mass or biological body mass and on whether the prosthetic knee was passive or non-passive. Conclusions: Given that the post-limb loss model had numerous features that predisposed it to low metabolic cost, these results suggest transfemoral limb loss per se increases the metabolic cost of walking. However, the large differences above able-bodied peers of ∼20-45% in most gait analysis experiments may be avoidable, even when minimizing deviations from able-bodied gait mechanics. Portions of this text were previously published as part of a preprint (https://www.biorxiv.org/content/10.1101/2023.06.26.546515v2.full.pdf).

Post-Traumatic Osteoarthritis, Psychological Health, and Quality of Life After Lower Limb Injury in U.S. Service Members.

INTRODUCTION: The aims of this project were to assess (1) the prevalence and timing of post-traumatic osteoarthritis (PTOA) after a traumatic lower limb injury, (2) the risk of PTOA based on injury type, and (3) the association of PTOA with psychological health and quality of life (QoL). MATERIALS AND METHODS: The Wounded Warrior Recovery Project (WWRP) database and the Expeditionary Medical Encounters Dataset were queried to identify service members injured during deployment. The Military Health System Data Repository was utilized to extract medical record data to identify individuals with PTOA. Data on PTSD, depression symptoms, and QoL were extracted from the WWRP. RESULTS: Of the 2,061 WWRP participants with lower limb injuries, 124 (6%) were diagnosed with PTOA, with first PTOA diagnosis occurring 3.8 ± 3.1 years after injury. Of the injury categories identified, only fractures were associated with high odds of lower limb PTOA (adjusted odds ratio [OR] = 3.92, 95% confidence interval [CI]: 2.38, 6.44). Individuals with PTOA diagnoses reported lower QoL scores relative to those without PTOA (F(1,2057) = 14.21, B = -0.05, P < .05). Additionally, rates of PTSD and depression symptoms were high but not different between those with or without PTOA. CONCLUSIONS: Despite a low prevalence of lower limb PTOA in our study, fractures increased the risk of PTOA after deployment-related injuries. Additionally, those with PTOA reported lower QoL scores relative to those without PTOA. The findings of this study highlight the personalized needs of patients with trauma beyond just the repair of the immediate injury.

Weight Changes in Young Service Members After Lower Limb Amputation: Insights From Group-Based Trajectory Modeling.

INTRODUCTION: Weight gain can contribute to osteoarthritis, cardiovascular disease, low back pain, and poor health-related quality of life. Weight trajectory patterns have been described in older veterans with limb loss; however, there is limited evidence of changes in weight in younger veterans with limb loss. MATERIALS AND METHODS: Service members with unilateral or bilateral lower limb amputations (LLAs) (and without an upper limb amputation) were included in this retrospective cohort analysis (n = 931). The mean postamputation baseline weight was 78.0 ± 14.1 kg. Bodyweight and sociodemographic data were extracted from clinical encounters within electronic health records. Group-based trajectory modeling assessed weight change patterns 2 years postamputation. RESULTS: Three weight change trajectory groups were identified: 58% (542 of 931) of the cohort had stable weight, 38% (352 of 931) had weight gain (mean gain = 19.1 kg), and 4% (31 of 931) had weight loss (mean loss = 14.5 kg). Individuals with bilateral amputations were more frequently noted in the weight loss group compared with those with unilateral amputations. Individuals with LLAs because of trauma other than blasts were more frequently found in the stable weight group compared with those with amputations because of disease or a blast. Younger individuals (<20 years old) with amputations were more likely to be in the weight gain group compared with older individuals. CONCLUSIONS: More than half the cohort maintained a stable weight for two years after amputation, and more than a third experienced weight gain during the same time frame. Knowledge of underlying factors that were associated with weight gain could inform preventative strategies for young individuals with LLAs.

Comparison of five different methodologies for evaluating ankle-foot orthosis stiffness.

BACKGROUND: The mechanical properties of an ankle-foot orthosis (AFO) play an important role in the gait mechanics of the end user. However, testing methodologies for evaluating these mechanical properties are not standardized. The purpose of this study was to compare five different evaluation frameworks to assess AFO stiffness. METHOD: The same 13 carbon composite AFOs were tested with five different methods. Four previously reported custom test fixtures (the BRUCE, KST, SMApp, and EMPIRE) rotated an AFO into dorsiflexion about a defined axis in the sagittal plane. The fifth method involved quasi-static deflection of AFOs into dorsiflexion by hanging weights (HW) from the footplate. AFO rotational stiffness was calculated as the linear fit of the AFO resistive torque and angular deflection. Differences between methods were assessed using descriptive statistics and a repeated measures Friedman with post-hoc Bonferroni-Holm adjusted Wilcoxon signed-rank tests. RESULTS: There were significant differences in measured AFO stiffnesses between test methods. Specifically, the BRUCE and HW methods measured lower stiffness than both the EMPIRE and the KST. Stiffnesses measured by the SMApp were not significantly different than any test method. Stiffnesses were lowest in the HW method, where motion was not constrained to a single plane. The median difference in absolute AFO stiffness across methods was 1.03 Nm/deg with a range of [0.40 to 2.35] Nm/deg. The median relative percent difference, measured as the range of measured stiffness from the five methods over the average measured stiffness was 62% [range 13% to 156%]. When the HW method was excluded, the four previously reported test fixtures produced a median difference in absolute AFO stiffness of 0.52 [range 0.38 to 2.17] Nm/deg with a relative percent difference between the methods of 27% [range 13% to 89%]. CONCLUSIONS: This study demonstrates the importance of developing mechanical testing standards, similar to those that exist for lower limb prosthetics. Lacking standardization, differences in methodology can result in large differences in measured stiffness, particularly for different constraints on motion. Non-uniform measurement practices may limit the clinical utility of AFO stiffness as a metric in AFO prescription and future research.

Footwear limitations in women prosthesis users relate to more than preference.

BACKGROUND: The option to wear desired footwear may be an important part of community reintegration after lower-limb amputation. OBJECTIVES: This study explored outcomes related to footwear, health, and participation in women Veterans with lower-limb amputation. METHODS: A cross-sectional questionnaire was mailed to all women Veterans age 18-82 years with major lower-limb amputation(s) who had received prosthetics services in the US Department of Veterans Affairs (N = 538). The questionnaire assessed Perceived Challenges (including clothing limitations, prosthetic foot limitations [width, height, and shape], and shoe avoidance for safety concerns), type of footwear used and preference, and included subscales from the Patient-Reported Outcome Measurement Information System, Amputee Body Image Scale Prosthetic Limb Users' Survey of Mobility, Community Participation Index, Activities-Specific Balance Confidence Scale, and Prosthesis Evaluation Questionnaire. Bivariate correlations examined relationships between a composite measure of Perceived Challenges and patient-reported outcomes. RESULTS: One hundred questionnaires were returned (18.6% response rate; 3 excluded for limited prosthesis use). The Perceived Challenges score was significantly correlated with scores for the Amputee Body Image Scale-Revised (r = 0.24, p = 0.019), Patient-Reported Outcome Measurement Information System (ability to participate: r = -0.25, p = 0.014), Prosthesis Evaluation Questionnaire (utility: r = -0.32, p = 0.001, appearance: r = -0.48, p < 0.001), Activities-Specific Balance Confidence Scale (r = -0.20, p = 0.046), and Prosthetic Limb Users' Survey of Mobility (r = -0.21, p = 0.036), but not depression or anxiety. CONCLUSIONS: Women who have greater issues with how their prosthesis affects the shoes and clothing they can wear also have poorer body image, reduced functional capabilities, and lower reported participation in activities. Improved prosthetic foot design may help to improve social participation and other important outcomes for women prosthesis users.

Uneven Treadmill Training for Rehabilitation of Lateral Ankle Sprains and Chronic Ankle Instability: Protocol for a Pragmatic Randomized Controlled Trial.

BACKGROUND: Lateral ankle sprains (LASs) are common injuries among military service members. Approximately 40% of individuals with an LAS progress to develop chronic ankle instability (CAI), a condition that results in substantial mechanical and neurophysiological impairment and activity limitation. Since proprioceptive and balance training improve functional outcomes and prevent secondary injury following LAS, they are recommended in clinical practice. Uneven treadmills are an innovative modality that challenge the sensorimotor system while performing an ecologically valid task simulating environments frequently encountered by service members with LAS and CAI. OBJECTIVE: The aim of this study is to evaluate whether the inclusion of uneven treadmill training in standard rehabilitation can improve clinical, functional, biomechanical, and patient-reported outcomes compared with the standard of care alone in service members with LAS and CAI. The prophylactic effects of treatment on secondary injury and identification of any contributing or mediating factors that influence outcomes following treatment will also be evaluated. We hypothesize that service members receiving uneven treadmill training will demonstrate greater improvements in clinical and instrumented measures of impairment, patient-reported function, and lower risk of injury recurrence than the control group immediately post and 18 months following treatment. METHODS: A multisite, parallel randomized clinical trial will be performed among service members aged 18-49 years being treated for LAS and CAI in military treatment facilities in the United States. Participants randomly assigned and allocated to receive the experimental intervention will be provided up to 12 sessions of training on an uneven terrain treadmill over a 6-week treatment course to supplement standard rehabilitation care. Treatment intensity of the rehabilitation exercises and treadmill training will be progressed on the basis of patient-perceived intensity and treatment responses. Outcome measures will include patient-reported outcomes, functional assessments, performance measures, and biomechanical measures. Investigators collecting outcome measures will be blinded to treatment allocation. Reinjury rates and patient-reported outcomes of function will be tracked over 18 months following treatment. RESULTS: The project was funded in September 2020. Patient recruitment began in November 2021, with 3 participants enrolled as of February 2022. Dissemination of the main study findings is anticipated in 2024. CONCLUSIONS: This study will assess the impact of an innovative uneven-terrain treadmill on treatment outcomes in the rehabilitation of service members with LAS and CAI. The results of this study will be used to inform rehabilitation practices and to potentially improve functional outcomes and secondary prevention in this patient population. TRIAL REGISTRATION: ClinicalTrials.gov NCT04999904; https://clinicaltrials.gov/ct2/show/NCT04999904?term=NCT04999904. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/38442.

Effect of Custom Carbon Ankle-Foot Orthosis Use on Energetic Demands of Walking and Comparisons With Individuals With Amputation.

OBJECTIVE: To compare the metabolic demands of walking in individuals with lower limb injury with and without ankle-foot orthosis (AFO) use. A secondary aim was to compare these results with those from individuals with unilateral transtibial amputation (TTA) and able-bodied controls. DESIGN: Cross-sectional study. SETTING: Two clinical research centers. PARTICIPANTS: Thirteen individuals (N=13) with lower limb injury who used a passive-dynamic AFO underwent metabolic analysis at 3 standardized speeds with and without their AFO. Results were compared with individuals with unilateral TTA who used a passive prosthetic foot and able-bodied controls with no musculoskeletal, neurologic, or cardiovascular deficits. MAIN OUTCOME MEASURES: Oxygen consumption, heart rate, and rating of perceived exertion. RESULTS: The use of the passive-dynamic AFO did not significantly change energetic demand (oxygen consumption, heart rate, perceived exertion) in participants with a lower limb [LL] injury. Heart rate (P<.037) was significantly greater than able-bodied controls, but perceived exertion was significantly lower (P≤.031). There were no significant differences between participants with an LL injury (with or without the AFO) and individuals with TTA. CONCLUSIONS: Many individuals with LL injuries may expect to use passive-dynamic AFOs with little to no metabolic consequence. The stabilizing and assistive benefits of the AFO likely balance with its well-known range of motion limitations and power reductions. Passive-dynamic AFO use can sometimes be an alternative for individuals considering TTA. These results support that AFO users may be able to achieve similar energetic demands as those with amputation.

Effects of women's footwear on the mechanical function of heel-height accommodating prosthetic feet.

The loaded mechanical function of transtibial prostheses that result from the clinical assembly, tuning, and alignment of modular prosthetic components can directly influence an end user's biomechanics and overall mobility. Footwear is known to affect prosthesis mechanical properties, and while the options of footwear are limited for most commercial feet due to their fixed geometry, there exists a selection of commercial prosthetic feet that can accommodate a moderate rise in heel height. These feet are particularly relevant to women prosthesis users who often desire to don footwear spanning a range of heel heights. The aim of this study was to assess the effects of adding women's footwear (flat, trainer, 5.08 cm heel) on the mechanical properties (deformation and energy efficiency) of four models of heel-height accommodating prosthetic feet. Properties were measured through loading-unloading at simulated initial contact, midstance and terminal stance orientations with a universal materials test system, and statistically compared to a barefoot condition. Results suggest that the addition of footwear can alter the level of foot deformation under load, which may be a function of the shoe and alignment. Moreover, while each foot displayed different amounts of energy storage and return, the addition of footwear yielded similar levels of energy efficiency across foot models. Overall, prosthesis users who don shoes of varying heel heights onto adjustable prosthetic feet and their treating clinicians should be aware of the potential changes in mechanical function that could affect the user experience.

Multiplanar Stiffness of Commercial Carbon Composite Ankle-Foot Orthoses.

The mechanical properties of an ankle-foot orthosis (AFO) can impact how a user's movement is either restricted or augmented by the device. However, standardized methods for assessing stiffness properties of AFOs are lacking, posing a challenge for comparing between devices and across vendors. Therefore, the purpose of this study was to quantify the rotational stiffness of thirteen commercial, nonarticulated, carbon composite ankle-foot orthoses. A custom, instrumented test fixture, for evaluating mechanical properties in rotating exoskeletons (EMPIRE), deflected an AFO through 20 deg of plantar/dorsiflexion motion about a specified, but adjustable, ankle axis. Sagittal, frontal, and transverse plane rotational stiffness were calculated, and reliability was assessed between cycles, sessions, and testers. The EMPIRE demonstrated good-to-excellent reliability between testers, sessions, and cycles (intraclass correlation coefficients all ≥0.95 for sagittal plane stiffness measures). Sagittal plane AFO stiffness ranged from 0.58 N·m/deg to 3.66 N·m/deg. AFOs with a lateral strut demonstrated frontal plane stiffnesses up to 0.71 N·m/deg of eversion while those with a medial strut demonstrated frontal plane stiffnesses up to 0.53 N·m/deg of inversion. Transverse plane stiffnesses were less than 0.30 N·m/deg of internal or external rotation. These results directly compare AFOs of different models and from different manufacturers using consistent methodology and are intended as a resource for clinicians in identifying a device with stiffness properties for individual patients.

Transtibial limb loss does not increase metabolic cost in three-dimensional computer simulations of human walking.

Loss of a lower limb below the knee, i.e., transtibial limb loss, and subsequently walking with a prosthesis, is generally thought to increase the metabolic cost of walking vs. able-bodied controls. However, high-functioning individuals with limb loss such as military service members often walk with the same metabolic cost as controls. Here we used a 3-D computer model and optimal control simulation approach to test the hypothesis that transtibial limb loss in and of itself causes an increase in metabolic cost of walking. We first generated N = 36 simulations of walking at 1.45 m/s using a "pre-limb loss" model, with two intact biological legs, that minimized deviations from able-bodied experimental walking mechanics with minimum muscular effort. We then repeated these simulations using a "post-limb loss" model, with the right leg's ankle muscles and joints replaced with a simple model of a passive transtibial prosthesis. No other changes were made to the post-limb loss model's remaining muscles or musculoskeletal parameters compared to the pre-limb loss case. Post-limb loss, the gait deviations on average increased by only 0.17 standard deviations from the experimental means, and metabolic cost did not increase (3.58 ± 0.10 J/m/kg pre-limb loss vs. 3.59 ± 0.12 J/m/kg post-limb loss, p = 0.65). The results suggest that transtibial limb loss does not directly lead to an increase in metabolic cost, even when deviations from able-bodied gait mechanics are minimized. High metabolic costs observed in individuals with transtibial limb loss may be due to secondary changes in strength or general fitness after limb loss, modifiable prosthesis issues, or to prioritization of factors that affect locomotor control other than gait deviations and muscular effort.

Should I Stay or Should I Go? Identifying Intrinsic and Extrinsic Factors in the Decision to Return to Duty Following Lower Extremity Injury.

INTRODUCTION: Rehabilitation research of wounded service members (SMs) commonly focuses on physical ability to return to duty (RTD) as a measure of successful recovery. However, numerous factors or barriers may influence a SM's ability and/or desire to RTD after lower extremity musculoskeletal trauma. SMs themselves as well as the clinical care team that works with them daily, often for years at a time, both offer unique perspectives on the influential factors that weigh into decisions to RTD. The purpose of this study was to identify the intrinsic and extrinsic factors patients and clinicians recognized as influencing the decision to RTD after severe lower extremity trauma. MATERIALS AND METHODS: Thirty-two SMs with severe lower extremity trauma (amputation and lower limb salvage) and 30 providers with at least 2 years' experience caring for SMs with similar injuries participated separately in either a SM or provider/clinician focus group. Open-ended questions on factors influencing RTD and other rehabilitation success were discussed. Data analysis consisted of qualitative transcription and participatory active sorting, followed by thematic coding and grouping of qualitative data. RESULTS: Individual (health condition, personal traits, and career consideration), interpersonal (clinician's impact, family influence, and peer influence), health care system (systems of care, transdisciplinary rehabilitation, and innovation availability), and institutional (policy, benefits, and unit/commander) themes emerged amongst SM patients and clinicians. Expected frequently occurring themes common to both groups were the influence of the team and family unit, as well as career trajectory options after a severe injury. An unexpected theme was acknowledgment of and dissatisfaction with the recent dismantling of institutional systems that support wounded SMs. Patients placed less emphasis on severity of injury and greater emphasis on system and policy barriers than did clinicians. CONCLUSIONS: Characterization and classification of these clinician and SM-identified factors that influence the decision to RTD after severe lower extremity trauma is expected to improve the efficacy of future rehabilitation efforts and clinical practice guidelines by providing the clinical team the knowledge necessary to recognize modifiable barriers to patient success. A better understanding of factors influencing RTD decision-making may support policies for mitigating RTD barriers, better monitoring of the changing landscape of RTD after lower extremity trauma, improving systems of health care, and/or reducing turnover and facilitating force readiness.

The effect of custom carbon ankle-foot orthosis alignment on roll-over shape and center of pressure velocity.

BACKGROUND: Maintaining an optimal rolling of the foot over the ground is thought to increase the stability and efficiency of pathologic gait. Ankle-foot orthoses are often prescribed to improve gait mechanics in individuals with lower extremity injuries; however, their design may compromise how the foot rolls over the ground. OBJECTIVES: The aim of this study was to investigate the effects of the sagittal plane ankle-foot orthosis alignment on roll-over shape and center of pressure velocity in individuals with lower limb reconstructions. STUDY DESIGN: Randomized cross-over study with a control group comparison. METHODS: In total, 12 individuals with lower limb reconstruction who used a custom carbon ankle-foot orthosis and 12 uninjured controls underwent gait analysis. Ankle-foot orthosis users were tested in their clinically-provided ankle-foot orthosis alignment, with an alignment that was 3° more plantarflexed, and with an alignment that was 3° more dorsiflexed. Components of roll-over shape and center of pressure velocity were calculated from heel strike on the ankle-foot orthosis limb to contralateral heel strike. RESULTS: Roll-over shape radius was not affected by 3° changes to alignment and was not significantly different from controls. Aligning the ankle-foot orthosis in more dorsiflexion than clinically provided resulted in a smaller peak center of pressure velocity that occurred later in stance. CONCLUSION: Individuals using custom carbon ankle-foot orthoses can accommodate 3° alterations in the dorsiflexion or plantarflexion alignment.

Resolving the Burden of Low Back Pain in Military Service Members and Veterans (RESOLVE): Protocol for a Multisite Pragmatic Clinical Trial.

BACKGROUND: Physical therapy (PT) is frequently used for the management of low back pain (LBP) within the US Departments of Defense (DOD) and Veterans Affairs (VA). However, variations in PT practice patterns and use of ineffective interventions lower the quality and increase the cost of care. Although adherence to the clinical practice guidelines (CPGs) can improve the outcomes and cost-effectiveness of LBP care, PT CPG adherence remains below 50%. The Resolving the Burden of Low Back Pain in Military Service Members and Veterans (RESOLVE) trial will evaluate the effectiveness of an active PT CPG implementation strategy using an education, audit, and feedback model for reducing pain, disability, medication use, and cost of LBP care within the DOD and VA health care systems. DESIGN: The RESOLVE trial will include 3,300 to 7,260 patients with LBP across three DOD and two VA medical facilities using a stepped-wedge study design. An education, audit, and feedback model will be used to encourage physical therapists to better adhere to the PT CPG recommendations. The Oswestry Disability Index and the Defense and Veterans Pain Rating Scale will be used as primary outcomes. Secondary outcomes will include the LBP-related medication use, medical resource utilization, and biopsychosocial predictors of outcomes. Statistical analyses will be based on the intention-to-treat principle and will use linear mixed models to compare treatment conditions and examine the interactions between treatment and subgrouping status (e.g., limb loss). SUMMARY: The RESOLVE trial will provide a pragmatic approach to evaluate whether better adherence to PT CPGs can reduce pain, disability, medication use, and LBP care cost within the DOD and VA health care systems.

Low back pain in persons with lower extremity amputation: a systematic review of the literature.

BACKGROUND CONTEXT: Lower extremity amputation (LEA) is associated with an elevated risk for development and progression of secondary health conditions. Low back pain (LBP) is one such condition adversely affecting function, independence, and quality of life. PURPOSE: The purpose of this study was to systematically review the literature to determine the strength of evidence relating the presence and severity of LBP secondary to LEA, thereby supporting the formulation of empirical evidence statements (EESs) to guide practice and future research. STUDY DESIGN/SETTING: Systematic review of the literature. METHODS: A systematic review of five databases was conducted followed by evaluation of evidence and synthesis of EESs. RESULTS: Seventeen manuscripts were included. From these, eight EESs were synthesized within the following categories: epidemiology, amputation level, function, disability, leg length, posture, spinal kinematics, and osseointegrated prostheses. Only the EES on epidemiology was supported by evidence at the moderate confidence level given support by eight moderate quality studies. The four EESs for amputation level, leg length, posture, and spinal kinematics were supported by evidence at the low confidence level given that each of these statements had some evidence not supporting the statement but ultimately more evidence (and of higher quality) currently supporting the statement. The remaining three EESs that addressed function, disability and osseointegrated prosthetic use were all supported by single studies or had comparable evidence that disagreed with study findings rendering insufficient evidence to support the respective EES. CONCLUSIONS: Based on the state of the current evidence, appropriate preventative and, particularly, treatment strategies to manage LBP in persons with LEA remain a knowledge gap and an area of future study.

Experimental comparisons of passive and powered ankle-foot orthoses in individuals with limb reconstruction.

BACKGROUND: Ankle-foot orthoses (AFO) are commonly prescribed to provide functional assistance for patients with lower limb injuries or weakness. Their passive mechanical elements can provide some energy return to improve walking ability, but cannot restore plantar flexor push-off. Powered AFOs provide an assistive torque about the ankle to address the limitations of passive devices, but current designs have yet to be implemented on a large scale clinically. PURPOSE: To compare passive AFOs to a new untethered, powered AFO design in a clinical population with lower limb reconstruction. METHODS: A crossover study design, conducted on three individuals with lower limb reconstruction, compared gait mechanics at a standardized speed (based on leg length) in 4 AFO conditions: 1. None (shoes only), 2. Blue Rocker (BR, Allard, USA), 3. Intrepid Dynamic Exoskeletal Orthosis (IDEO), and 4. PowerFoot Orthosis (PFO BionX Medical Technologies, Inc.). The PFO was a custom, battery-powered device whose damping and power were capable to being tuned to meet patient needs. Subjects performed biomechanical gait analysis and metabolic testing at slow, moderate and fast speeds. Dependent variables included total limb power (calculated using a unified deformable segment model), mechanical work, mechanical efficiency, ankle motion, net metabolic cost across three speeds, and performance measures were calculated. Effect sizes (d) were calculated and d > 0.80 denoted a large effect. RESULTS: Net positive work (d > 1.17) and efficiency (d > 1.43) were greatest in the PFO. There were large effects for between limb differences in positive work for all conditions except the PFO (d = 0.75). The PFO normalized efficiency between the affected and unaffected limbs (d = 0.50), whereas efficiency was less on the affected limb for all other conditions (d > 1.69). Metabolic rate was not consistently lowest in any one AFO condition across speeds. Despite some positive results of the PFO, patient preferred their daily use AFO (2 IDEO, 1 BR). All participants indicated that mass and size were concerns with using the PFO. CONCLUSIONS: A novel PFO resulted in more biomimetic mechanical work and efficiency than commercially-available and custom passive AFO models. Although the powered AFO provided some biomechanical benefits, further improvements are warranted to improve patient satisfaction.

Maintenance of muscle strength retains a normal metabolic cost in simulated walking after transtibial limb loss.

Recent studies on relatively young and fit individuals with limb loss suggest that maintaining muscle strength after limb loss may mitigate the high metabolic cost of walking typically seen in the larger general limb loss population. However, these data are cross-sectional and the muscle strength prior to limb loss is unknown, and it is therefore difficult to draw causal inferences on changes in strength and gait energetics. Here we used musculoskeletal modeling and optimal control simulations to perform a longitudinal study (25 virtual "subjects") of the metabolic cost of walking pre- and post-limb loss (unilateral transtibial). Simulations of walking were first performed pre-limb loss on a model with two intact biological legs, then post-limb loss on a model with a unilateral transtibial prosthesis, with a cost function that minimized the weighted sum of gait deviations plus metabolic cost. Metabolic costs were compared pre- vs. post-limb loss, with systematic modifications to the muscle strength and prosthesis type (passive, powered) in the post-limb loss model. The metabolic cost prior to limb loss was 3.44±0.13 J/m/kg. After limb loss, with a passive prosthesis the metabolic cost did not increase above the pre-limb loss cost if pre-limb loss muscle strength was maintained (mean -0.6%, p = 0.17, d = 0.17). With 10% strength loss the metabolic cost with the passive prosthesis increased (mean +5.9%, p < 0.001, d = 1.61). With a powered prosthesis, the metabolic cost was at or below the pre-limb loss cost for all subjects with strength losses of 10% and 20%, but increased for all subjects with strength loss of 30% (mean +5.9%, p < 0.001, d = 1.59). The results suggest that maintaining muscle strength may prevent an increase in the metabolic cost of walking following unilateral transtibial limb loss, and that a gait with minimal deviations can be achieved when muscle strength is sufficiently high, even when using a passive prosthesis.

Evaluation of NU-FlexSIV Socket Performance for Military Service Members with Transfemoral Amputation.

Ischial containment sockets are the current standard of care for military service members with transfemoral amputation. However, they fit intimately with the ischium, which may limit hip motion and contribute to proximal socket discomfort, a common complaint among prosthesis users. Subischial sockets, such as the newly described Northwestern University Flexible Subischial Vacuum (NU-FlexSIV) Socket technique, do not interact with the ischium, potentially increasing hip motion and improving comfort. PURPOSE: To transfer the NU-FlexSIV Socket technique to military prosthetists and evaluate performance among military service members with transfemoral amputation. STUDY DESIGN: case series. METHODS: Four of the 11 enrolled subjects completed the study protocol comparing the NU-FlexSIV Socket to the ischial containment socket. Gait kinematics (over ground and on stairs), physical performance measures (Four-Square Step Test, T-test of Agility, and an obstacle course), limb-socket motion, and socket comfort were assessed after accommodation time in each socket. RESULTS: While wearing the NU-FlexSIV Socket, sagittal plane hip motion generally increased while coronal plane trunk motion and walking speed remained largely unaffected during over ground walking. During stair ascent, sagittal plane hip motion increased while wearing the NU-FlexSIV Socket, with minimal changes in walking speed for all subjects. Pre- and post-walking fluoroscopy measures suggest fit of the NU-FlexSIV Socket was less affected by activity. Most subjects reported that the NU-FlexSIV Socket was more comfortable for sitting but some found it less comfortable for walking and running. Performance measure results were mixed. Although attempts were made to consistently implement the NU-FlexSIV Socket technique, some challenges were experienced. CONCLUSIONS: The NU-FlexSIV Socket provided greater hip motion across a variety of tasks without adversely affecting other movement mechanics but did not consistently improve socket comfort. Variability in the liners and socket materials used may have contributed to variability in results. Overall, the design was a viable alternative to traditional ischial containment sockets for some individuals with transfemoral amputation.

Creative prosthetic foot selection enables successful ambulation in stiletto high heels.

BACKGROUND: Walking in high heels presents biomechanical challenges, yet they remain part of many women's attire. However, women with a lower limb amputation are limited in available footwear options. Case description and methods: This case study is in response to one patient's assertion that she walked better and more symmetrically in heels than flat shoes with her below-knee prosthesis. She underwent gait analysis in athletic shoes and 10-cm stiletto high heels worn with a pediatric running foot to determine if these claims could be substantiated through biomechanical measures. Global gait asymmetry indices were calculated. Findings and outcomes: Asymmetry indices were nearly identical between athletic shoes and heels but joint-level findings differed substantially. Ankle mechanics were more symmetrical in heels but hip mechanics were less. CONCLUSION: The maintenance of symmetry in stiletto high heels does not imply maintenance of gait quality, as high heels are known to adversely affect some components walking mechanics. Clinical relevance Returning to high-heel wear is achievable for prosthesis users. Accommodations can be made using creativity in prosthetic foot selection to enable successful ambulation; however, attention to gait mechanics may be important for patient safety.

The influence of traumatic transfemoral amputation on metabolic cost across walking speeds.

BACKGROUND: Recent literature indicates equivalent costs of walking can be achieved after a transtibial amputation when the individual is young, active, and/or has extensive access to rehabilitative care. It is unknown if a similar cohort with transfemoral amputation can also achieve lower metabolic costs of walking than previously reported. OBJECTIVE: Compare metabolic cost in individuals with a transfemoral amputation to controls and to the literature across a range of walking speeds. STUDY DESIGN: Cross-sectional. METHODS: A total of 14 individuals with a unilateral transfemoral amputation (27 ± 5 years, N = 4 mechanical knee, N = 10 microprocessor knee) and 14 able-bodied controls (26 ± 6 years) walked at self-selected and four standardized speeds. Heart rate, metabolic rate (mL O2/kg/min), metabolic cost (mL O2/kg/m), and rating of perceived exertion were calculated. RESULTS: Self-selected speed was 8.6% slower in the transfemoral amputation group ( p = 0.031). Across standardized speeds, both metabolic rate and metabolic cost ranged from 44%-47% greater in the transfemoral amputation group ( p < 0.001), heart rate was 24%-33% greater ( p < 0.001), and perceived exertion was 24%-35% greater ( p < 0.009). CONCLUSION: Although the transfemoral amputation group was relatively young, physically fit, and had extensive access to rehabilitative care, the metabolic cost of walking fell within the ranges of the literature on older or presumably less fit individuals with transfemoral amputation. Clinical relevance Developments in prosthetic technology and/or rehabilitative care may be warranted and may reduce the metabolic cost of walking in individuals with a transfemoral amputation.